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Title:
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Inverse carbon dioxide flux estimates for the Netherlands
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Author(s):
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Meesters, A.G.C.A. ; Tolk, L.F. ; Peters, W. ; Hutjes, R.W.A.; Vellinga, O.; Elbers, J.A.; Vermeulen, A.T.; Laan, S. van der; Neubert, R.E.M.; Meijer, H.A.J.; Dolman, A.J.
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Published by:
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Publication date:
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ECN
Environment & Energy Engineering
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16-9-2012
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ECN report number:
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Document type:
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ECN-W--12-038
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Article (scientific)
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Number of pages:
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42
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Abstract:
CO2 fluxes for the Netherlands and surroundings are estimated for the year 2008, from
concentration measurements at four towers, using an inverse model. The results are
compared to direct CO2 flux measurements by aircraft, for 6 flight tracks over the
Netherlands, flown multiple times in each season. We applied the Regional Atmospheric
Mesoscale Modeling system (RAMS) coupled to a simple carbon flux scheme (including
fossil fuel), which was run at 10 km resolution, and inverted with an Ensemble Kalman
Filter. The domain had 6 eco-regions, and inversions were performed for the four seasons
separately. Inversion methods with pixel-dependent and -independent parameters for each
eco-region were compared. The two inversion methods, in general, yield comparable flux
averages for each eco-region and season, whereas the difference from the prior flux may
be large. Posterior fluxes co-sampled along the aircraft flight tracks are usually much
closer to the observations than the priors, with a comparable performance for both
inversion methods, and with best performance for summer and autumn. The inversions
showed more negative CO2 fluxes than the priors, though the latter are obtained from a
biosphere model optimized using the Fluxnet database, containing observations from
more than 200 locations worldwide. The two different crop ecotypes showed very
different CO2 uptakes, which was unknown from the priors. The annual-average uptake is
practically zero for the grassland class and for one of the cropland classes, whereas the
other cropland class had a large net uptake, possibly because of the abundance of maize
there.
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